A boy celebrating his birthday was mauled by a sea lion when a holiday trip to the zoo turned to terror.

Ronnie Green’s horrified parents could only look on helplessly as the 20 stone beast sank its teeth into their son’s leg during what was meant to be a fun “swim with the sea lions” treat for his 10th birthday.

Before the incident, Ronnie was photographed playing happily with the female sea lion and rubbing noses with her by the poolside.

But just minutes later the sea lion ripped a chunk out of his leg and he had to be dragged screaming from the pool.

His mum Vanessa said: “There was nothing I could do apart from scream too. Ronnie was pulled out and my husband Steven carried him up the hill. There was blood everywhere. He was hysterical.

“In some ways, he is lucky to be alive. If it had bitten him on the face or in the neck goodness knows what would have happened.”

Vanessa, 44, of Hertford, said the attack last month at Jungle Park in popular Tenerife holiday spot Los Cristianos, came out of the blue.

She said: “We were watching as he met the sea lion and jumped in the water.

“They seemed to be having a great time in the pool for the first five minutes. Then suddenly, it just turned on him. I was watching through the glass – there was nothing I could do.”

Ronnie said: “The sea lion just dived in and went straight for my leg. It was scary.”

Vanessa said staff at the wildlife park didn’t provide any medical help – just put them in a taxi to the hospital where her son had temporary stitches.

She added: “It ruined the rest of Ronnie’s holiday.

“When we got back home we went to hospital and they had to clean it out again. He’s still having his bandages changed every other day and we’re going back to the hospital once a week.”

The incident will cast fresh doubt on the safety of swimming with captive animals and on the conditions in which they are kept.

Vanessa said: “There comes a point when you have to blame the people who have them captive and not the animal.”